The low water level is seen at the Stonecliffe boat launch in Head, Clara and Maria Township on Sunday, May 7, while those living along the Ottawa River downstream and other waterways have been flooded out.Ryan Paulsen / -

The Ottawa River between Rolphton and Mattawa is exceedingly low, according to locals, while whole urban neighbourhoods 200 kilometres downstream are under water.

How could this be so?

“I haven’t seen the water this low in 40 years,” says Bob Brunette, 69, a trapper in the Upper Ottawa Valley, who sends along photos of a partially dry riverbed near a tiny place along Highway 17 called Deux Rivières. The images only add to the photos in the Pembroke Observer showing docks at nearby Stonecliffe high and dry.

Doug Antler has run the Kingfisher Lodge, a fishing/hunting outfitter and campground, at Deux Rivières for 34 years, during which he’s seen the river go up and down like a yo-yo and even helped monitor water levels. He believes the downstream floods this year were partially man-made because “two-and-a-half feet” of water was drawn down on his stretch — and sent downstream — on April 27.

“They didn’t have to dump that water.”

(By “stretch” he means a run of about 70 kilometres long and about a kilometre wide. Note the Ottawa area got overrun about a week after the upstream dump — aided, of course, by a massive pile of rain.)

There is an explanation, of course. Today, with hundreds of residents suffering property damage in the millions, it just doesn’t seem very persuasive.

Here’s my best attempt at an answer, with apologies to Michael Sarich, a senior regulating engineer at the Ottawa River Regulating Committee, for over-simplifying.

Think of the far upstream Ottawa as a series of giant bathtubs, which are the northern reservoirs, and the river as a set of connected pipes that take the tub-water downstream. Feeding into those pipes along the 1,300-km way are smaller pipes, being the tributaries.

When the bathtub fills in the spring, it has to be emptied. But the sections of pipe, which have hydro dams, can’t all accept water at the same rate, because the pipes have jagged bottoms or take wicked bends.

In the 85-km run between Mattawa and Rolphton, the river is often narrow and has “natural restrictions,” like a bottom that rises from 100 metres deep to eight, and a bunch of islands. So, like a pipe with rocks in the middle and then twisty corners. When you try to push too much water in the rocky pipe, it backs up, and backing up means flooding.

So, in preparation for emptying the bathtub, the water in the narrow pipes is kept low so they can take the tub’s overflow.

“When you hold that water under high (spring) flows, it backs water further up the system,” says Sarich. “So if Da Swisha (Des Joachims dam at Rolphton) was held, say, at its normal levels, the town of Mattawa would be under water.”

So you lower the water in these sections constricted with natural funnels. And it’s all very noticeable, says Sarich, when highways come close to the river and motorists can see stumps on the riverbed just as their radios are telling them about cars under water in Gatineau.

“The question occurs not just this year, but every year.”

Ontario Power Generation reports that river levels upstream of the Des Joachims dam are about 1.4 metres below summer levels (150.89 metres today versus 152.3 in summer), and are this much lower for about 50 kilometres. Though that seems like an ungodly amount of water, Sarich says, in the scheme of the whole system, it isn’t that much.

The regulating committee says there are three spots on the system that regularly draw attention during the spring drawdown: upstream of Des Joachims, Chats Falls (Arnprior) and the Carillon dam near Hawkesbury. People hear of floods, yet see exposed river rocks, says Sarich.

“It’s not like anybody’s asleep at the switch,” said Sarich. “It’s a difficult thing to explain. It’s a common thing that people really struggle with.”

Absolutely. There hasn’t been a public meeting yet this week where residents haven’t wondered what on Earth is going on with water management on the greater Ottawa system, which has 25 dams and 15 reservoirs.

The Ottawa River Regulation Planning Board, which runs the “regulating committee,” was formed in 1983 and has three federal members, and two each from Ontario and Quebec.

Among the members are the ministries of natural resources in Ontario and Quebec, Hydro Quebec and Ontario Power Generation, Public Works, Environment Canada and the Canadian Coast Guard.

Antler said he was at a golf tournament in Renfrew this week and river levels were all anyone could talk about.

“We never used to have any of these problems. But these guys are hydrologists. They think they know what makes sense.”

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